Means for overcoming fan-out in lithograph press

ABSTRACT

An infeed mechanism including an oscillating transfer assembly for gripping the straight leading edge of a sheet in a sheet-fed press and for transferring it to grippers on a rotating cylinder in a bowed condition in order to overcome the tendency for the trailing portion of the sheet to spread or fan-out as it is acted upon by the press cylinders. The transfer assembly has gripper pads which are in general alinement but which are moved into the locus of a bow during a stroke of swinging movement for progressively deforming the leading edge of the sheet into a bow from the time that the sheet is engaged to the time that the sheet is released to the grippers on the rotating cylinder. In the preferred embodiment the gripper pads on the transfer assembly are mounted upon a pad bar which is progressively bowed in one direction as the transfer assembly is swung into its sheet pick-up position and then progressively restored to its straight position and into a bow of opposite direction as the transfer assembly is swung to the position where the sheet is released to the grippers on the constantly rotating cylinder. Means are provided for varying the amount of bow in the bar including levers on the transfer assembly which are actuated by a cam and cam follower which move relatively to one another as the transfer assembly swings back and forth.

United States Paten 1191 Smith Sept. 3, 1974 MEANS FOR OVERCOMINGFAN-OUT IN LITHOGRAPH PRESS Walter S. Smith, Naperville, Ill.

[73] Assignee: Rockwell International Corporation,

Pittsburgh, Pa.

[22] Filed: Apr. 17, 1972 [21] Appl. No.: 244,387

[75] Inventor:

Primary ExaminerEvon C. Blunk Assistant ExaminerBruce l-I. Stoner, Jr.

[57] ABSTRACT An infeed mechanism including an oscillating transferassembly for gripping the straight leading edge of a sheet in asheet-fed press and for transferring it to grippers on a rotatingcylinder in a bowed condition in order to overcome the tendency for thetrailing portion of the sheet to spread or fan-out as it is acted uponby the press cylinders. The transfer assembly has gripper pads which arein general alinement but which are moved into the locus of a bow duringa stroke of swinging movement for progressively deforming the leadingedge of the sheet into a bow from the time that the sheet is engaged tothe time that the sheet is released to the grippers on the rotatingcylinder. ln the preferred embodiment the gripper pads on the transferassembly are mounted upon a pad bar which is progressively bowed in onedirection as the transfer assembly is swung into its sheet pick-upposition and then progressively restored to its straight position andinto a bow of opposite direction as the transfer assem- 9 Claims, 16Drawing Figures .SMITH J N+ WALTERS 3 I PATENTEO 35? 31974 a v Q3 A TYS;

PAIENIEMEP 3mm MET 30$ 4 lavas-ran WALTER 8. 8mm

Atty;

j l7 Iuvsuron WALTER '5. SMITH MEANS FOR OVERCOMING FAN-OUT INLITHOGRAPH PRESS It is an object of the present invention to provide aninfeed mechanism for a rotary sheet-fed printing press in which theoscillating transfer assembly has a set of gripper pads for gripping thestraight leading edge of the sheet and for progressively deforming theleading edge into a bowed condition as the sheet is swung toward thepoint where the sheet is released to grippers on an associatedconstantly rotating cylinder. It is a more specific object of theinvention to provide a transfer assembly having bar-mounted gripper padsand in which means are provided for gradually or progressively deformingthe bar to vary the bowed condition of the bar as the transfer assemblyis swung between its sheet engaging and sheet releasing positions. Thearrangement is thus distinguished over prior bowing arrangements havinga pad bar and in which the pad bar is bent into a bowed configuration asa result of engaging adjustable stops at the limit of its swingingmovement. Consequently it is an object of the invention to provide aninfeed mechanism in which the bowing and pick-up functions occursmoothly and quietly and which may be operated at high press speeds.

It is a related object to provide an infeed mechanism for a rotarysheet-fed printing press which is highly versatile, permitting anydesired degree or direction of bowing, which is easily adjustable, andwhich, once adjusted, reliably retains its adjustment over long pressruns. It is a general object to provide an infeed mechanism which is ofinherently economical construction and which operates reliably, withminimum maintenance, 'over long periods of time.

Other objects and advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawings in which:

FIG. 1 is a front view of a pad bar assembly in accordance with thepresent invention looking along line I-l in FIG. 3.

FIG. 2 is a top view of thestructure looking along line 2-2 in FIG. 1.

FIG. 3 is a vertical section taken'through the transfer assembly alongthe line 33 in FIG. 2.

FIG. 3a is an enlarged cross section taken through the pad bar andshowing the feedtable and shaft which operates the gripper fingers.

FIG. 3b is a fragmentary bottom view lookingalong the line 3b3b in FIG.3

FIG. 4 is a simplified section similar to FIG. 3 but showing transfer ofa sheet to the constantly running cylinder.

FIG. 5 is a side view of a central supporting bracket looking along line5-5 in FIG. 2.

FIG. 6 is a transverse section along line 66 of FIG. 2 and showing onesupport bracket for the pad bar control lever.

FIG. 7 is a transverse section taken along line 77 of FIG. 2 and showingthe other support bracket for the pad bar control lever.

FIG. 8 is a plan view of a cam supporting bracket.

FIGS. 9, 9a and 9b are stop motion views showing the travel of the camfollower along the cam.

FIGS. 10, 10a and 10b are stop motion views showing the progressivedeformation of the pad bar andthe sheet which is transported by the padbar.

While the invention'has been described in connection with a preferredembodiment, it will be understood that I do not intend to limit theinvention to the particular embodiment shown but intend on the contraryto cover the various alternative and equivalent constructions includedwithin the spirit and scope of the appended claims.

Turning now to the drawings and particularly to FIGS. 1-5, there isdisclosed a portionof a sheet-fed lithograph press having a frame 10(see also FIG. 8) and a feed table I I (FIG. 3a) onto which sheets arefed, one by one, from left to right as viewed in the drawings, againstfront register stops I3. The latter are mounted upon a shaft 14. Atypical sheet, indicated at I5, has a straight leading edge 16, lateraledges 17,18 and a trailing edge 19. The front register stops 13 areprovided for the purpose of accurately defining the position of theleading edge of the sheet in readiness for pick-up in proper phaserelation for transfer'to grippers on a constantly rotating impressioncylinder. Thefront register stops are physically separate from the table11, and it will be understood that they may be separately adjustedforwardly or backwardly with respect to the length dimension of thesheet or skewed slightly as desired.

For the purpose of picking up a stationary sheet at the leading edge andfor accelerating it to press speed an oscillating transfer assembly 30is provided formed of a cylindrical drumlike member 31 having endmembers 33, 34 and with journals 35, 36 on the cylinder axis, whichjournals are mounted in suitable hearings in the press frame 10 foroscillation back and forth. The transfer assembly 30 swings from theposition shown in FIG. 3,. where the stationary sheet is gripped, to theposition shown in FIG. 4 where the sheet has accelerated to press" speedand at which point transfer takes place to a set of grippers 41 mountedupon a constantly rotating impression cylinder 40. After a certainamount of overtravel, the transfer assembly decelerates and reverses itsmovement to return to the pick-up position shown in FIG. 3. The meansfor oscillating the assembly 30 is not included within the scope of thepresent invention, and reference may be made to the prior art fortypical oscillating drive such, for example, as that shown in priorpatent 1,764,104.

For the purpose of gripping the leading edge of a sheet a pad bar 50 isprovided having a series of gripper pads including a set of centralgripper pads 51 and a' set of gripper pads 52 at the opposite ends ofthe bar. Taking a gripper pad 51 by way of example (FIG. 3a) it has ananchoring portion 56, a sheet engaging pad surface 57 and an angledentry leg 58' for guiding the leading edge 16 of the sheet into positionfor gripping. Cooperating with sets of pads 51, 52 are sets of gripperfingers 61, 62 which are mounted upon a shaft 60. Means not shown butwell understood by those skilled in the art are provided for impartingrocking movement to the shaft 60 whereby the gripper fingers thereon arecaused to grip a sheet when the transfer assembly is in the position ofpick up shown :in FIG. 3 and release the sheet immediately followingtransfer shown in FIG. 4. It is one of the features of the presentconstruction that the pad surface '57 on each of the pads is roughenedwhereas the gripping surface on each of the cooperating fingers 61, 62is smooth. Thus when the pad bar 50 flexes or bows, as will bediscussed, the leading edge of the sheet will move with the pads, andslip relative to the fingers.

In carrying out the present invention the pad bar 50 is rigidly mountedwith respect tothe cylinder 31 at its center and is mounted at its endsfor limited movement in a peripheral direction relative to the cylinder.Thus, referring to FIGS. 1 and 2, the central portion of the bar ismounted upon brackets 71 which are secured to pads 72 which are weldedto the cylinder 31 in depending position. Secured to the brackets 71'are supports 73 which are bolted to the bar by bolts 74. Extendingthrough the members 71, 73 is a registering opening 75 in which a rollerbearing 76 is fitted, the shaft 60, which mounts the fingers 61, 62,extending through the central race. A total of two of such fixed bracketassemblies are used in the central position, corresponding numeralsbeing used to designate corresponding parts.

While the central portion of the pad'bar 50 is fixed with respect to thetransfer assembly by brackets 71, 73, the endsof the pad bar are notpositively anchored but are mounted for slight relative or floatingmovement with respect to the assembly. Thus, adjacent each end of thebar 50 is a bracket 80 which is secured to the cylinder 31 and whichmounts a bolt 81 having a washer. 82 and collar 83, the collar extendingthrough a clearance opening 84 in the bar and the length of the collarbeing such as to provide forward and back clearance 85, 86. To providesupport for the end of the bar in the radial direction, however, aspring plate 87 of rectangular configuration is used, the outer end ofwhich is securely clamped to the bracket 80 and the inner end of whichis clamped to the bar by a pair of cap screws 88.

To provide additional support for the bar 50 at points intermediate thecenter and the ends of the bar, brackets 91 are provided mounted ,uponrespective pads 92 and each carrying a support 93 having a bolt 94, thehead of which extends into a clearance opening 95 formed in the bar.Radial support is provided by a spring plate 96 of rectangular shapewhich is secured to the support 93 at the center and the ends of whichare clamped to the bar by cap screws 97, 98. Corresponding structure isused at the corresponding offcenter location.

Since the spring plates 87 and 96 have a high degree of rigidity in theradial direction they support the bar 50 against possible deflection bycentrifugal force and yet enable the bar to bow freely, in theperipheral sense, in one direction or the other. The bar is sufficientlythin so that a reasonable force suffices to produce the slight bendingrequired.

In accordance with the present invention a cam and cam follower areprovided between the movable portions of the bar (in this case the ends)and the frame of the machine, for operation progressively during astroke of oscillating movement, so that the sheet is gripped with thepads occupying a first bowed locus and released to the constantlyrotating cylinder with the pads occupying a second bowed locus with theleading edge of the sheet being progressively deformed into abow. In thepresent instance the cam, indicated at 100, has an arcuate inner surface101-l04 which is engaged by a cam follower in the form of a roller 105,on a pin 106, the cam surface being arcuately disposed about the axis ofthe transfer assembly and so arranged that the cam follower roller iscammed radiallyinward as the transfer'ass'embly rocks to its limit ofclockwise movement. For transmitting the movement of the cam followerroller a lever 110 is provided which has an upwardly extending arm 11],which is curved to follow the contour of the drum 31, and a shortdownwardly extending arm 112, making the lever of dog-leg shape.

Extending through the bend of the dog-leg is a transverse pivot pin 113which is journaled in alined bearings 114, 115. The pin 113 is held inplace by a clamping member 116 in the form of an elongated lug which isscalloped out as indicated at 117 and which is threaded and providedwith a nut 118.at its outer end. Tightening the nut 118 draws the lug116 endwise, thereby clamping the pin tightly in position.

For transmitting the motion of the lever to the pad bar, a bracket 120is provided in the form of a clevis (FIG. 3b) having sides 121, 122which embrace the lower end 112 of the lever 110, the bracket beingsecured to the end of the bar by means of a bolt 123. To hold the lowerend of the lever captive in the clevis, and to permit relative rockingmovement, a bearing 125 is provided having a central opening 126 throughwhich the shaft 60 which mounts the cyclical fingers 61, 62, extends. Anannular clearance space 127 is provided between the shaft 60 and theinner race of the bearing 125 so that limited movement of the bracket120 may occur without any necessity for bending the shaft 60.

In order to maintain the cam follower roller 105 bottomed on the camsurface a spring 130 is used which is held in place by a first. pin 131near the tip of the lever and by a second pin 132 which isfastened to ananchoring pad 133- on the drum 31.

For the purpose of mounting the bearings 114 and 115, a bearing mountingassembly (FIGS. 6 and 7) is provided having bearing blocks 141, 142. Thebearing block 141 is mounted upon the transfer cylinder 31 by means ofbolts 143 which are threaded into a pad 144 welded or otherwise securedto the cylinder 31. The bearing block 142 is essentially a mirror imageof block 141 and it is secured by bolts 145 to a similar pad 146 weldedto the cylinder 31. The bearing blocks each have a groove 147 to fitover tongues 148 on the respective pads 144 and 146 for alinementpurposes and, when initially assembled,'the blocks are adjusted axiallyrelative to each other to remove all looseness or play in the bearingsbefore they are bolted in position. Corresponding structure isemployedat the opposite end of the bar 50, operating in synchronism, and thesame reference numerals have been used.

For the purpose of defining a reference position for the transferassembly and'the central gripper pads 51 at the center of the bar 50 andwhich are effectively fixed to the assembly, the end plates 33, 34 areextended upwardly as shown in profile in FIG. 3, terminatingin stops 150which strike respective stops 151 fixed with respect to the frame. Thedegree of bow which is imparted to the leading edge of the sheettherefore depends upon the locus of the gripper pads when the transferassembly is in its reference position, at the time that the gripperfingers are closed, as well as upon the subsequent bowing movement ofthe pad bar during its swing intothe position where the sheet istransferred to the grippers on the constantly rotating companioncylinder.

In operation, then, as the cam follower is swung on the transferassembly, from the region 103, through the region 102 to the region 101of the cam surface, i.e.,

to the position shown in FIG. 3, inward crowding of the follower rollercauses the lever 110 to rock about the axis of the pivot pin 113 througha small angle in the counterclockwise direction to retract theassociated end of the bar so that the bar is bowed to place the padsthereon in the locus of a bow in readiness for gripping the straightleading edge of the sheet.

Further in accordance with the invention the arcuate surface l0ll04 ofthe cam 100 is formed so as to be concentric with the axis ofoscillation of cylinder 31 to define a neutral condition in which thebar. 50 is straight, yet capable of cocking adjustment in eitherdirection about a central pivot axis to vary both the amount anddirection of bow in the locus of the gripper pads which the camcontrols. Thus the cam 100, which is in the present construction ofboomerang profile is pivoted for cocking adjustment about a pin 160,mounting a bearing 161, which is secured to'the end of a bracket 162(FIG. 8) mounted upon one of the stationary'end frame members of thepress. For the purpose of imparting minute cocking adjustment to the cammember in one direction or the other, a manual control 170 is providedin a form of an adjusting shaft 171 having a shallow thread 172 which isscrewed into a threaded support 173, the degree of advancementof thethread being manually controllable by a knob 174. Rotation of the knobis limited to a useful range, in the present instance slightly lessthan.360, by a pin 175 on I the shaft which engages a stop pin 176. Thesupport 173, into which the shaft is screwed, is supported on a bracket177 .in the form of a flat, horizontally extending rigid plate which isfirmly secured to the frame10 on the press.

Arranged in the path of movement of the adjusting shaft 171 is a bellcrank 180 having a first leg 181 and a second leg 182 pivoted about acentral axis 183. The leg 182 of the bell crank is pinned at 184 to adrop link 185, the lower end of which is pinned at 186 to one end of thecam member. For removing from the linkage system any possible loosenessor play, a stiff spring 187 is interposed between the stationary bracket177 and the cam. The spring is centered about a pin 188 on the cam andengages, at its upper end, a threadedly adjustable seat member 189 whichpermits adjustment of the spring pressure. The spring force issufficiently great so that the spring maintains the bell crank firmlyseated against the adjusting screw regardless of the normallyencountered variations in reaction pressure between the cam follower andthe cam. The force originating in the take-up spring 187 also has theeffect of removing any endwise play in the tread 172 of the adjustingshaft 171 so that even the minutest amount of adjusting movement of theknob 174 results in an accurately corresponding degree of cockingmovement of the cam.

Corresponding adjusting structure, in a mirror image, is employed forthe cam 100 at the opposite end of the transfer assembly. Because of thecomplete take-up of the play at both ends, corresponding movements ofthe adjusting knobs can be expected to produce corresponding amounts ofbow in the locus of the gripper pads mounted on the pad bar.

Under normal circumstances, where it is desired to impart a convex bowto the leading edge of a sheet for overcoming fan-out,,the cam 100 isadjusted by rotating the adjusting shaft so as to rock the bell crank180 counterclockwise, cocking the cam'clockwise from its neutralposition so that the cam occupies the position shown, greatlyexaggerated for clarity, in FIG. 9. When the transfer assembly 30 isrocked to its reference position, defined by the stops 150, 151, forpick-up, the cam follower occupies the position 101 on the cam surfacein which the follower is pressed radially inward against the force ofthe spring 130, causing the levers at the ends of the bar to rockslightly counterclockwise, pulling upon the ends of the bar 50, so thatthe bar, and the gripper pads 51, 52 which are mounted thereon, as wellas the intermediate gripper pads. occupy a convexly bowed locus at thetime that the gripper fingers are closed against the pads. as shown inFIG. 10. This closure, of itself, does not deform the leading edge ofthe sheet. However, when the transfer assembly begins to swingcounterclockwise, relative movement occurs between the cam followers andthe respective cams, advancing the followers to the region 102 of thecam surface, alined with the pins 160 which support the cam members. Byreason of the alinement, the region 102 is a neutral region, which isunaffected by the cocking of the cam member. As the cam followersproceed to the neutral position, they are moved radially outward byfollow-up expansion of the spring 130, causing the pad bar to berestored to its straight condition as shown in FIG. 10a. This causes thegripper pads 52 at the ends of the bar to move relatively in thedirection of the sheet so that the lateral edges of the sheet retreatslightly, accompanied by convex bowing at the leading edge.

. As the transfer assembly swings further in the counterclockwisedirection the follower roller 105 proceeds from the neutral point 102 tothe position 103 corresponding to release of the sheet to the gripperson the constantly running cylinder. Such movement, from 102 to 103, isaccompanied by an additional movement of the follower roller radiallyoutward with respect to the transfer cylinder, which results inclockwise relative rocking of the levers 110 and pushing of the pad bar50 by supports at each end. This forms the pad bar In short, it will beseen that one-half of the bowing of the leading edge of the sheet occursduring the first half of the swing, until the pad bar at mid-pointoccupies its straight condition, the other half occurring during thefinal portion of the swing until the pad bar is bowed in its oppositedirection. This enables maximum antifanout effect with a minimumdeflection of the pad bar from its neutral condition. It is to be notedthat the leading edge of the sheet is deformed from its straightcondition to its bowed condition progressively during the time that itis being transported, enabling the entire sheet to be graduallyaccommodated to the convexity at the leading edge over the entiretransport stroke.

The bowing is accomplished both smoothly and gradually and the structurei-sithus distinguished over prior structures where the bowing iscontrolled by stops which deflect the pad bar to the required extentduring the final movement of the transfer assembly into its referencepick-up position. The transfer assembly then overtravels to the to theposition 104 on the cam 100 to clear" the gripper fingers. Upon thereturn stroke of swinging movement the sequence automatically reverses.i

While it is one of the features of the Construction that the locus ofthe pads changes gradually from bowing in one direction to bowing in theopposite direction over the transport stroke, it will be apparent thatthe invention is not limited'thereto and the invention may be practicedwith bowing of the pad bar in a single direction only. For example, bymoving the lever pivot pin 160 from the position shown in FIG. 3 toposition'101 on the cam surface, the sheet may be picked up with the padbar in its straight condition, and all of the bow ing movement may beimparted to the sheet by bowing of the bar in the direction shown inFIG. 10b. Conversely, the pivot pin 160 may be moved into alinement withthe portion of the surface 103 of the cam, whereupon'the pad barwill bebowed, as shown in FIG. 10, at the time of pick-up and straightened, asshown in FIG. 10a at the time'of transfer to the grippers on theconstant rotating cylinder.

Also while it is one of the features of the present con struction thatthe gripper pads 51, 52 are distributed at the central and end positionson a continuous supporting bar, it will be apparent to one skilled inthe art that the invention, in one of its aspects, is not limited to useof a bowed bar and that the gripper pads 52 may be separately mountedfor individual peripheral movement and directlycoupled to the lower endof the lever 110 for direct positioning by the latter. For example, thepads 52 might be mounted as slides in peripherally extending ways for,limited forward and backward movement without departing from theinvention. Alternatively, the gripper pads might be mounted on a radialarm secured to the cylinder 31 and having sufficient flexibility so asto permit limited movement, under the control of lever 110, in theperipheral direction.

Also, while means have been shown for anchoring the central portion ofthe bar 50 and imparting limited relative movement to' the ends, theinvention is not limited thereto and, if desired, the ends of the barmay be relatively fixed, as regards movement in the peripheraldirection, to the transfer assembly, while the central portion of thebar is floatingly mounted and movable by a single lever such as thelever 110 disclosed in the drawings.

As used herein the term sheet register guides refers to any means forholding and positioning the straight leading edge of the sheet forpick-up by the gripper pads.

I claim as my invention:

I. An infeed mechanism for a rotary sheet-fed printing press for feedingsheets to grippers on a constantly rotating cylinder comprising, incombination, a frame including a feed table for receiving sheets fed oneby one, a set of front register guides for engaging and positioning theleading edge of an advancing sheet, a transfer assembly having meansoscillating the same for picking up the straight leading edge of thesheet at the register guides and accelerating the sheet to press speedfor transfer to the grippers on the rotating cylinder, said transferassembly including an axially extending pad bar having a plurality ofgripper pads mounted therealong, the pads having respective coactinggripper fingers, the pad bar being secured at its center to the transferassembly and mounted for limited movement in the peripheral direction atits ends, means for defining the limit of movement of the transferassembly to establish a reference position for the bar, means forclosing the gripper fingers on the pads at the limit position forgripping the leading edge of the sheet, cam members mounted on the frameat the ends of the transfer assembly and presenting respective arcuatecam surfaces which are substantially concentric with the axis ofoscillation, cam followers coupled to the ends'of the pad bar forengaging the respective cam surfaces, each of the cam members beingpositionable to define a neutral position for the cam follower at whichthe pad bar is substantially straight and having provision for precisecocking adjustment so that the bar is bowed in one direction at the timeof gripping the leading edge of the sheet and bowed in the oppositedirection at the time the sheet is released to the grippers of theconstantly rotating cylinder thereby to progressively deform the leadingedge of the sheet from a straight condition to a bowed condition fortransfer to the cylinder grippers to compensate for fan-out at thetrailing edge.

2. An infeed mechanism for a rotary sheet-fed printing press for feedingsheets to grippers on a constantly rotating cylinder comprising, incombination, a frame including a feed table for receiving sheets fed oneby one, a set of front register guides for engaging and positioning thestraight leading edge of an advancing sheet, a transfer assembly havingmeans for oscillating the same for picking up the leading edge of thesheet at the register guides and for accelerating the sheet to pressspeed for transfer to the grippers on the rotating cylinder, saidtransfer assembly having a series of generally alined gripper padsincluding respective sets of pads at the center and at the ends of thetransfer assembly, at least one set of the pads being fixed to thetransfer assembly, said pads having respective coacting gripper fingers,means for defining the limit of movement of the transfer assembly tomomentarily position the said one set of pads in a reference grippingposition, means for closing the gripper fingers on the pads to grip theleading edge of the sheet, the other set of gripper pads being mountedon the transfer assembly for limited relative movement in the peripheraldirection and having means for shifting in either direction from thestraight condition into a bowed locus, cam and cam follower meansinterposed between the shifting means and the frame to produceprogressive relative movement of the shifting means over a stroke ofoscillation of the transfer assembly, the cam being so contoured as tocause the locus of the gripper pads to be bowed in one direction at thetime of gripping the leading edge of the sheet and to be bowed in theother direction at the time that the sheet is released to the gripperson the constantly rotating cylinder thereby to deform the leading edgeof the sheet from the straight condition to a bowed condition forcompensation for fan-out-at the trailing edge.

3. An infeed mechanism for a rotary sheet-fed printing press for feedingsheets to grippers on a constantly rotating cylinder comprising, incombination, a frame including a feed table for receiving sheets fed oneby one, a set of front register guides for engaging and positioning theleading edge of the advancing sheet, a transfer assembly having meansfor oscillating the same for picking up the straight leading edge of thesheet at the register guides and for accelerating the sheet to pressspeed for transfer to the grippers on the rotating cylinder, saidtransfer assembly having a series of aligned fining the limit ofmovementof the transfer assembly for momentarily positioning the saidone set of pads in a reference gripping position, means for closing thegripper fingers on the pads to grip the leading edge of the sheet, theother set of gripper pads being mounted on the transfer assembly forlimited relative movement in the peripheral direction and having meansfor shift-' ing the same with respect to the assembly so that the padsoccupya bowed locus at the instant of gripping, cam means on the frameadjustably mounted with respect to the frame for varying the maximumthrow of the cam and thereby varying the curvature of the locus of thepads at the instant of gripping, said cam means having a cam surfaceextending arcuately about-the transfer assembly, cam follower meanscoupledto the shifting means for engaging the camrneans, the cam surfacehaving a shallow throw and being of such contour that the pads are movedinto a bowed locus progressively with movement of the transfer assemblytoward the reference position followed by movement'of the padsprogressively into straight position as the transfer assembly reversesits movement, thereby to impart a bow of opposite curvature to theleading edge of the sheet for compensation for fan-out at the trailingedge.

4. An infeed mechanism for a rotary sheet-fed printing press for feedingsheets to grippers on a constantly rotating cylinder comprising, incombination, a frame including a feed table for receiving sheetsfed oneby one, a set of front register guides for engaging and positioning theleading edge of the advancing sheet, a transto bow in the oppositedirection at the instant of transfer of the sheet to the rotatingcylinder.

5. An infeed mechanism for a rotary sheet-fed printing press for feedingsheets to grippers on a constantly rotating cylinder comprising, incombination, a frame including a feed table for receiving sheets fed oneby one, a set of front register guides for engaging and positioning theleadingedge of the advancing sheet, a transfer assembly having means foroscillating the same for picking upthe straight leading edge of thesheet at the register guides and for accelerating the sheet to pressspeed for transfer to the grippers on the rotating cylinder, saidtransfer assembly having a-s'eries of aligned gripper pads includingrespective sets of pads at the center and at the ends of the transferassembly, at least one set of the pads being fixed to the transferassembly, said pads having coacting gripper fingers, means for definingthe limit of movement of the transfer assembly for momentarilypositioning the said one set of pads in a reference gripping position,means for closing the gripper fingers on the pads to grip the leadingedge of the sheet, the other set of gripper pads being mounted on thetransfer assembly for limited relative movement in the peripheraldirection and having means for shifting the same with respect to theassembly so that the pads occupy a bowed locus at the instant ofgripping, cam means on the frame having a cam surface extendingarcuately about the transfer assembly and being concentric with the axisof oscillation of the transfer assembly to provide zero throwof the camfollower and in which adjusting means are provided for'adjustably ferassembly having means for oscillating the same for I center and at theends of the transfer assembly, at least one set of the pads being fixedto the transfer assembly,

said pads having coacting gripper fingers, means for defining the limitof movement of the transfer. assembly for momentarily positioning thesaid one set of pads-in a reference gripping position, means for closingthe gripper fingers on the pads to grip the leading edge of the sheet,the other set of gripper pads being mounted -on the transfer assemblyfor limited relative movement in the peripheral direction ahd havingmeans for shifting the same with respect to the assembly so that thepads occupy a bowed locus atthe instant of gripping, cam means on theframe having a cam surface extending arcuately about the transferassembly, cam follower means coupled to the shifting means for engagingthe cam means, the cam surface having a shallow throw and being of suchcontour that, the pads are moved into a bowed locus progressively withmovement of the transfer assembly toward the reference position followedby movement of the pads progressively into straight position as thetransfer assembly reverses its movement thereby to impart a bow ofopposite curvature to the leading edge of the sheet for compensation forfan-out at the trailing edge, the cam means being so shaped as to causethe locus of the gripper 'pads to bow in one direction at the instant ofgripping the sheet and cocking the cam means to produce a desired degreeand direction of bowing of the locus of the gripper pads at therespective gripping and release of the sheet, cam follower means coupledto the shifting means for engaging the cam means, the cam surface havinga shallowthrow and being of such contour that the pads are moved into abowed locus progressively with movement of the transfer assembly towardthe reference position followed by movement of the pads progressivelyinto straight position'as the transfer assembly reverses its movementthereby to impart a bow of opposite curvature to the leading edge-of thesheet for compensation for fan out at the trailing edge. 1

1 6. An infeed mechanism for arotary sheet-fed printing press forfeeding sheets to grippers on a constantly rotating cylinder comprising,in combination, a frame including a feed table for receiving sheets fedone by one, a set of frontregister guides for engaging and positioningthe leading edge of the advancing sheet, a transfer assembly havingmeans for oscillating the same for picking up the straight leading edgeof the sheet at the register guides and for accelerating the sheet topress speed for transfer to thegrippers on the rotating cylinder, .saidtransfer assembly having a series of aligned gripper pads includingrespective sets of pads at the center and at the ends of the transferassembly, at least one set of the pads being fixed to the transferassembly, saidpads having coacting gripper fingers, means for definingthe limit of movement, of the transfer assembly for momentarilypositioning the said one set of pads in a reference gripping position,means for closing the gripper fingers on the pads to grip the leadingedge of the sheet, the other set of gripper pads being mounted on thetransfer assembly, for limited relative movement in the peripheraldirection andhaving means for shifting the same with respect to theassemblyso that the pads occupy a bowed locus at the instant ofgripping, cam means on the frame having a cam surface extendingarcuately about the transfer assembly and being substantially concentricwith the axis of oscillating movement of the transfer assembly, said cammeans being centrally pivoted with means including an adjusting screwfor rocking the cam means about the pivot in one direction or the other,cam follower means coupled to the shifting means for engaging the cammeans, the cam surface having a shallow throw and being of such contourthat the pads are moved into a bowed locus progressively with movementof the transfer assembly toward the reference position followed bymovement of the pads progressively into straight position as thetransfer assembly reverses its movement thereby to impart a bow ofopposite curvature to the leading edge of the sheet for compensation forfan-out at the trailing edge.

7. An infeed mechanism for a rotary sheet-fed printing press for feedingsheets to grippers on a constantly rotating cylindercomprising, incombination, a frame including a feed table for receiving sheets fed oneby one, a set of front register guides for engaging and'positioning theleading edge of the advancing sheet, a transfer assembly havingv meansfor oscillating the same for pickingup the straight leading edge of' thesheet at the register guides and for accelerating the sheet to pressregister guides and accelerating the sheet to press speed for transferto the grippers on the rotating cylinder, said transfer assembly havingrespective sets of gripper pads at the center and at the ends in generalalinement with one another, the pads having coacting gripper fingers,means for closing the gripper fingers on the pads to grip the-leadingedge of the sheet, at least one set of the pads being movable through asmall displacement relative to the transfer assembly and having meansfor shifting the pads relative to the assembly so that the padsoccupy abowed locus at the instant of gripping, means including a cam followeron the transfer assembly and a cam on the frame for operating theshifting means, a spring on the transfer assembly for maintaining thecam follower at all times in firm contact with the surface of the cam,the cam having a cam surface which is substantially concentric with thespeed for transfer to the grippers on the rotatingcylinder, -saidtransfer assembly having a series of aligned gripper pads includingrespective sets of pads-at the center and at the ends of the transferassembly, at least one set of the pads being fixed to the transferassembly, said pads having coacting gripper fingers, means for definingthe limit of movement of the transfer assembly for momentarilypositioning the said one set of pads in a reference gripping position,means for closing the gripper fingers on the pads to grip the leadingedge of the sheet, the other set of gripper pads being mounted on thetransfer assembly for limited relative movement in the peripheraldirection and having means for shifting the same with respect to theassembly so that the pads occupy a bowed locus at the instant ofgripping, cam means on the frame having a cam surface extendingarcuately about the transfer assembly, cam follower means coupled'to theshifting means for engaging the cam means, the cam surface having ashallow throw and being of such contour that the pads are moved into abowed locus progressively with movement of the transfer assembly towardthe reference position followed by movement of the pads progressivelyinto straight position as the transfer assembly reverses its movementthereby to impart a bow of opposite curvature to the leading edge of thesheet for compensation for fan-out at the trailing edge, said gripperpads each having a roughened surface and each coacting gripper fingerhaving a smooth surface so that the sheet tends to move with the padandrelative to the finger to put the leading edge of the sheet intobowed configuration.

8. An infeed mechanism for a rotary sheet-fed printing press for feedingsheets to grippers on a constantly rotating cylinder comprising, incombination, a frame including a feed table for receiving sheets fed oneby one, a set of front register guides for engaging and positioning thestraight leading edge of an advancing sheet, a transfer assembly havingmeans for oscillating the same for picking up the leading edge of thesheet at the axis of oscillating movement of the transfer assembly andhaving means for supporting the same for cooking movement thereby todetermine the throw of the cam follower, a manually operated adjustinglinkage coupled to the cam for holding it in a desired position ofadjustment, and means including a strong spring for constant take-up ofany play in the linkage means.

9. An infeed-mechanism for a rotary sheet-fed printing press for feedingsheetsto grippers on a constantly rotating cylinder comprising, incombination, a frame including a feed table for receiving sheets fed oneby one, a set of front register guides for engaging and positioning theleading edge of the advancing sheet, a transfer assembly having meansfor oscillating the same for picking up the leading edge of the sheet atthe register guides and for accelerating the sheet to'press speed fortransfer to the grippers on arotating cylinder, said transfer assemblyincluding an axially extending pad bar having a plurality of gripperpads thereon in general alinement including a central set and a set atthe respective ends of the bar, at least one of the sets being movablethrough a small displacement in a peripheral direction relative to thetransfer assembly so that the pads occupy a bowed locus, thepad barhaving supporting levers in its regions of movement, each of the leversbeingof dog-leg-shape centrally pivoted to the transfer assembly andhaving a radially extending arm for engaging the bar and a peripherallyextending arm having a cam follower mounted at theend thereof, cammembers on the framerespectively alined with the cam followers and eachhaving-an arcuate inwardly facing surface on-which the associated camfollower rides, springs on the transferassembly for pressing the camfollowers against the cam surfaces, the cam members being pivoted to theframe aboutvan axis parallel to the axis of oscillation, manualadjusting linkage for cocking each cam member into an adjustedpositionthereby to determine the amount of throw of the cam and hence the amountof bowing'imparted to the locus' of the pads, means for constantlystressing the cam member thereby to take up any play in theadjustinglinkage, means for establishing the limit of movement of thetransfer assembly to define a reference position for pick-up, and meansfor closing the gripper fingers on the pads to grip the leading edge ofthe sheet at the reference-position so that when the transfer assemblyreverses its movement the change in the curvature of the locus of thegripper pads imparts a bow to the leading edge of the sheet forcompensation for fan-out at the trailing edge. a a j"

1. An infeed mechanism for a rotary sheet-fed printing press for feedingsheets to grippers on a constantly rotating cylinder comprising, incombination, a frame including a feed table for receiving sheets fed oneby one, a set of front register guides for engaging and positioning theleading edge of an advancing sheet, a transfer assembly having meansoscillating the same for picking up the straight leading edge of thesheet at the register guides and accelerating the sheet to press speedfor transfer to the grippers on the rotating cylinder, said transferassembly including an axially extending pad bar having a plurality ofgripper pads mounted therealong, the pads having respective coactinggripper fingers, the pad bar being secured at its center to the transferassembly and mounted for limited movement in the peripheral direction atits ends, means for defining the limit of movement of the transferassembly to establish a reference position for the bar, means forclosing the gripper fingers on the pads at the limit position forgripping the leading edge of the sheet, cam members mounted on the frameat the ends of the transfer assembly and presenting respective arcuatecam surfaces which are substantially concentric with the axis ofoscillation, cam followers coupled to the ends of the pad bar forengaging the respective cam surfaces, each of the cam members beingpositionable to define a neutral position for the cam follower at whichthe pad bar is substantially straight and having provision for precisecocking adjustment so that the bar is bowed in one direction at the timeof gripping the leading edge of the sheet and bowed in the oppositedirection at the time the sheet is released to the grippers of theconstantly rotating cylinder thereby to progressively deform the leadingedge of the sheet from a straight condition to a bowed condition fortransfer to the cylinder grippers to compensate for fan-out at thetrailing edge.
 2. An infeed mechanism for a rotary sheet-fed printingpress for feeding sheets to grippers on a constantly rotating cylindercomprising, in combination, a frame including a feed table for receivingsheets fed one by one, a set of front register guides for engaging andpositioning the straight leading edge of an advancing sheet, a transferassembly having means for oscillating the same for picking up theleading edge of the sheet at the register guides and for acceleratingthe sheet to press speed for transfer to the grippers on the rotatingcylinder, said transfer assembly having a series of generally alinedgripper pads including respective sets of pads at the center and at theends of the transfer assembly, at least one set of the pads being fixedto the transfer assembly, said pads having respective coacting gripperfingers, means for defining the limit of movement of the transferassembly to momentarily position thE said one set of pads in a referencegripping position, means for closing the gripper fingers on the pads togrip the leading edge of the sheet, the other set of gripper pads beingmounted on the transfer assembly for limited relative movement in theperipheral direction and having means for shifting in either directionfrom the straight condition into a bowed locus, cam and cam followermeans interposed between the shifting means and the frame to produceprogressive relative movement of the shifting means over a stroke ofoscillation of the transfer assembly, the cam being so contoured as tocause the locus of the gripper pads to be bowed in one direction at thetime of gripping the leading edge of the sheet and to be bowed in theother direction at the time that the sheet is released to the gripperson the constantly rotating cylinder thereby to deform the leading edgeof the sheet from the straight condition to a bowed condition forcompensation for fan-out at the trailing edge.
 3. An infeed mechanismfor a rotary sheet-fed printing press for feeding sheets to grippers ona constantly rotating cylinder comprising, in combination, a frameincluding a feed table for receiving sheets fed one by one, a set offront register guides for engaging and positioning the leading edge ofthe advancing sheet, a transfer assembly having means for oscillatingthe same for picking up the straight leading edge of the sheet at theregister guides and for accelerating the sheet to press speed fortransfer to the grippers on the rotating cylinder, said transferassembly having a series of aligned gripper pads including respectivesets of pads at the center and at the ends of the transfer assembly, atleast one set of the pads being fixed to the transfer assembly, saidpads having coacting gripper fingers, means for defining the limit ofmovement of the transfer assembly for momentarily positioning the saidone set of pads in a reference gripping position, means for closing thegripper fingers on the pads to grip the leading edge of the sheet, theother set of gripper pads being mounted on the transfer assembly forlimited relative movement in the peripheral direction and having meansfor shifting the same with respect to the assembly so that the padsoccupy a bowed locus at the instant of gripping, cam means on the frameadjustably mounted with respect to the frame for varying the maximumthrow of the cam and thereby varying the curvature of the locus of thepads at the instant of gripping, said cam means having a cam surfaceextending arcuately about the transfer assembly, cam follower meanscoupled to the shifting means for engaging the cam means, the camsurface having a shallow throw and being of such contour that the padsare moved into a bowed locus progressively with movement of the transferassembly toward the reference position followed by movement of the padsprogressively into straight position as the transfer assembly reversesits movement, thereby to impart a bow of opposite curvature to theleading edge of the sheet for compensation for fan-out at the trailingedge.
 4. An infeed mechanism for a rotary sheet-fed printing press forfeeding sheets to grippers on a constantly rotating cylinder comprising,in combination, a frame including a feed table for receiving sheets fedone by one, a set of front register guides for engaging and positioningthe leading edge of the advancing sheet, a transfer assembly havingmeans for oscillating the same for picking up the straight leading edgeof the sheet at the register guides and for accelerating the sheet topress speed for transfer to the grippers on the rotating cylinder, saidtransfer assembly having a series of aligned gripper pads includingrespective sets of pads at the center and at the ends of the transferassembly, at least one set of the pads being fixed to the transferassembly, said pads having coacting gripper fingers, means for definingthe limit of movement of the transfer assembly for momentarilypositioning the said one sEt of pads in a reference gripping position,means for closing the gripper fingers on the pads to grip the leadingedge of the sheet, the other set of gripper pads being mounted on thetransfer assembly for limited relative movement in the peripheraldirection ahd having means for shifting the same with respect to theassembly so that the pads occupy a bowed locus at the instant ofgripping, cam means on the frame having a cam surface extendingarcuately about the transfer assembly, cam follower means coupled to theshifting means for engaging the cam means, the cam surface having ashallow throw and being of such contour that the pads are moved into abowed locus progressively with movement of the transfer assembly towardthe reference position followed by movement of the pads progressivelyinto straight position as the transfer assembly reverses its movementthereby to impart a bow of opposite curvature to the leading edge of thesheet for compensation for fan-out at the trailing edge, the cam meansbeing so shaped as to cause the locus of the gripper pads to bow in onedirection at the instant of gripping the sheet and to bow in theopposite direction at the instant of transfer of the sheet to therotating cylinder.
 5. An infeed mechanism for a rotary sheet-fedprinting press for feeding sheets to grippers on a constantly rotatingcylinder comprising, in combination, a frame including a feed table forreceiving sheets fed one by one, a set of front register guides forengaging and positioning the leading edge of the advancing sheet, atransfer assembly having means for oscillating the same for picking upthe straight leading edge of the sheet at the register guides and foraccelerating the sheet to press speed for transfer to the grippers onthe rotating cylinder, said transfer assembly having a series of alignedgripper pads including respective sets of pads at the center and at theends of the transfer assembly, at least one set of the pads being fixedto the transfer assembly, said pads having coacting gripper fingers,means for defining the limit of movement of the transfer assembly formomentarily positioning the said one set of pads in a reference grippingposition, means for closing the gripper fingers on the pads to grip theleading edge of the sheet, the other set of gripper pads being mountedon the transfer assembly for limited relative movement in the peripheraldirection and having means for shifting the same with respect to theassembly so that the pads occupy a bowed locus at the instant ofgripping, cam means on the frame having a cam surface extendingarcuately about the transfer assembly and being concentric with the axisof oscillation of the transfer assembly to provide zero throw of the camfollower and in which adjusting means are provided for adjustablycocking the cam means to produce a desired degree and direction ofbowing of the locus of the gripper pads at the respective gripping andrelease of the sheet, cam follower means coupled to the shifting meansfor engaging the cam means, the cam surface having a shallow throw andbeing of such contour that the pads are moved into a bowed locusprogressively with movement of the transfer assembly toward thereference position followed by movement of the pads progressively intostraight position as the transfer assembly reverses its movement therebyto impart a bow of opposite curvature to the leading edge of the sheetfor compensation for fan out at the trailing edge.
 6. An infeedmechanism for a rotary sheet-fed printing press for feeding sheets togrippers on a constantly rotating cylinder comprising, in combination, aframe including a feed table for receiving sheets fed one by one, a setof front register guides for engaging and positioning the leading edgeof the advancing sheet, a transfer assembly having means for oscillatingthe same for picking up the straight leading edge of the sheet at theregister guides and for accelerating the sheet to press speed fortransfer to the grippers on the rotatIng cylinder, said transferassembly having a series of aligned gripper pads including respectivesets of pads at the center and at the ends of the transfer assembly, atleast one set of the pads being fixed to the transfer assembly, saidpads having coacting gripper fingers, means for defining the limit ofmovement of the transfer assembly for momentarily positioning the saidone set of pads in a reference gripping position, means for closing thegripper fingers on the pads to grip the leading edge of the sheet, theother set of gripper pads being mounted on the transfer assembly forlimited relative movement in the peripheral direction and having meansfor shifting the same with respect to the assembly so that the padsoccupy a bowed locus at the instant of gripping, cam means on the framehaving a cam surface extending arcuately about the transfer assembly andbeing substantially concentric with the axis of oscillating movement ofthe transfer assembly, said cam means being centrally pivoted with meansincluding an adjusting screw for rocking the cam means about the pivotin one direction or the other, cam follower means coupled to theshifting means for engaging the cam means, the cam surface having ashallow throw and being of such contour that the pads are moved into abowed locus progressively with movement of the transfer assembly towardthe reference position followed by movement of the pads progressivelyinto straight position as the transfer assembly reverses its movementthereby to impart a bow of opposite curvature to the leading edge of thesheet for compensation for fan-out at the trailing edge.
 7. An infeedmechanism for a rotary sheet-fed printing press for feeding sheets togrippers on a constantly rotating cylinder comprising, in combination, aframe including a feed table for receiving sheets fed one by one, a setof front register guides for engaging and positioning the leading edgeof the advancing sheet, a transfer assembly having means for oscillatingthe same for picking up the straight leading edge of the sheet at theregister guides and for accelerating the sheet to press speed fortransfer to the grippers on the rotating cylinder, said transferassembly having a series of aligned gripper pads including respectivesets of pads at the center and at the ends of the transfer assembly, atleast one set of the pads being fixed to the transfer assembly, saidpads having coacting gripper fingers, means for defining the limit ofmovement of the transfer assembly for momentarily positioning the saidone set of pads in a reference gripping position, means for closing thegripper fingers on the pads to grip the leading edge of the sheet, theother set of gripper pads being mounted on the transfer assembly forlimited relative movement in the peripheral direction and having meansfor shifting the same with respect to the assembly so that the padsoccupy a bowed locus at the instant of gripping, cam means on the framehaving a cam surface extending arcuately about the transfer assembly,cam follower means coupled to the shifting means for engaging the cammeans, the cam surface having a shallow throw and being of such contourthat the pads are moved into a bowed locus progressively with movementof the transfer assembly toward the reference position followed bymovement of the pads progressively into straight position as thetransfer assembly reverses its movement thereby to impart a bow ofopposite curvature to the leading edge of the sheet for compensation forfan-out at the trailing edge, said gripper pads each having a roughenedsurface and each coacting gripper finger having a smooth surface so thatthe sheet tends to move with the pad and relative to the finger to putthe leading edge of the sheet into bowed configuration.
 8. An infeedmechanism for a rotary sheet-fed printing press for feeding sheets togrippers on a constantly rotating cylinder comprising, in combination, aframe including a feed table for receiving sheets fed one by one, a setof front register guides for engaging and positioning the straightleading edge of an advancing sheet, a transfer assembly having means foroscillating the same for picking up the leading edge of the sheet at theregister guides and accelerating the sheet to press speed for transferto the grippers on the rotating cylinder, said transfer assembly havingrespective sets of gripper pads at the center and at the ends in generalalinement with one another, the pads having coacting gripper fingers,means for closing the gripper fingers on the pads to grip the leadingedge of the sheet, at least one set of the pads being movable through asmall displacement relative to the transfer assembly and having meansfor shifting the pads relative to the assembly so that the pads occupy abowed locus at the instant of gripping, means including a cam followeron the transfer assembly and a cam on the frame for operating theshifting means, a spring on the transfer assembly for maintaining thecam follower at all times in firm contact with the surface of the cam,the cam having a cam surface which is substantially concentric with theaxis of oscillating movement of the transfer assembly and having meansfor supporting the same for cocking movement thereby to determine thethrow of the cam follower, a manually operated adjusting linkage coupledto the cam for holding it in a desired position of adjustment, and meansincluding a strong spring for constant take-up of any play in thelinkage means.
 9. An infeed mechanism for a rotary sheet-fed printingpress for feeding sheets to grippers on a constantly rotating cylindercomprising, in combination, a frame including a feed table for receivingsheets fed one by one, a set of front register guides for engaging andpositioning the leading edge of the advancing sheet, a transfer assemblyhaving means for oscillating the same for picking up the leading edge ofthe sheet at the register guides and for accelerating the sheet to pressspeed for transfer to the grippers on a rotating cylinder, said transferassembly including an axially extending pad bar having a plurality ofgripper pads thereon in general alinement including a central set and aset at the respective ends of the bar, at least one of the sets beingmovable through a small displacement in a peripheral direction relativeto the transfer assembly so that the pads occupy a bowed locus, the padbar having supporting levers in its regions of movement, each of thelevers being of dog-leg shape centrally pivoted to the transfer assemblyand having a radially extending arm for engaging the bar and aperipherally extending arm having a cam follower mounted at the endthereof, cam members on the frame respectively alined with the camfollowers and each having an arcuate inwardly facing surface on whichthe associated cam follower rides, springs on the transfer assembly forpressing the cam followers against the cam surfaces, the cam membersbeing pivoted to the frame about an axis parallel to the axis ofoscillation, manual adjusting linkage for cocking each cam member intoan adjusted position thereby to determine the amount of throw of the camand hence the amount of bowing imparted to the locus of the pads, meansfor constantly stressing the cam member thereby to take up any play inthe adjusting linkage, means for establishing the limit of movement ofthe transfer assembly to define a reference position for pick-up, andmeans for closing the gripper fingers on the pads to grip the leadingedge of the sheet at the reference position so that when the transferassembly reverses its movement the change in the curvature of the locusof the gripper pads imparts a bow to the leading edge of the sheet forcompensation for fan-out at the trailing edge.